Technical Abstract:
During the summer of 1993, three groups made acoustic measurements in various soils using a probe microphone. The probe microphone was a packaged system (Sabatier et al., 1995, Probe Microphone Instrumentation for Determining Soil Physical Properties: Testing in Model Porous Materials, Soil Technology, accepted for publication June, 1995) which allowed for collection of data by professionals not in the field of acoustics. Almost all soils tested were in soil boxes in both indoor and outdoor environments. The test media included gravel, sand, silt and loam. Layered soil systems were also used in the measurements. The sound attenuation and phase velocity data in the various soils are presented. A simple homogeneous acoustic model of the soil is used to predict acoustic flow resistivity and tortuosity as well as layer depths where appropriate. A layered porous soil model for the layer depth prediction was used. Conclusions as to the usefulness of the probe in agricultural soils are drawn.